Hydraulic valves for cam phasers are well known in the art. The hydraulic valves include a valve piston which is axially moveable in a valve housing of the hydraulic valve. Typically a first operating connection, a second operating connection and a supply connection are configured at the valve housing. The first operating connection and the second operating connection are connected with the cam phaser and a hydraulic fluid is feedable through these connections into the hydraulic valve and also out of the hydraulic valve. In order to supply the hydraulic valve with the hydraulic fluid fed by a feed device the valve housing includes the supply connection. The hydraulic fluid can flow through the hydraulic valve in different directions using a flowable channel system of the valve piston.
The valve piston is moved using an electromagnetic actuator. Thus the actuator includes a generally axially moveable plunger which is operatively connected with the valve piston. An axial movement of the plunger is transferred to the valve piston so that the valve piston changes its position within the hydraulic valve.
Since the hydraulic valve is flowed through by a hydraulic fluid, typically a hydraulic oil, the actuator has to be securely sealed relative to the hydraulic valve so that so that in particular a coil of the electromagnetic actuator is sealed against penetration of the hydraulic fluid.
Furthermore the coil has to be protected against a penetration of hydraulic fluid which is disposed in the actuator itself. This hydraulic valve is provided for moving an armature that is operatively connected to the plunger since the armature is moveably received in the actuator to provide axial movement to the plunger.
The publication document US 2006/0071560 A1 discloses an actuator which includes a sleeve for separating the coil from the hydraulic fluid that is necessary for moving the armature, wherein the armature is received axially moveable in an interior of the sleeve. The sleeve defines an interior of the sleeve relative to the cavity of the actuator, wherein the cavity is mostly defined by a coil carrier and a pole yoke. A pole core insert that is at least partially received in an interior of the sleeve closes the interior relative to a hydraulic valve which is arrangeable opposite to the pole core insert, so that the plunger of the actuator can move a valve piston of the hydraulic valve. The cavity is defined by a lip of the sleeve relative to a hydraulic fluid of the actuator, wherein the lip is configured as a lip disc that is provided with steps.
The printed document DE 10 2006 011 078 A1 discloses an actuator configured as a lift magnet which includes an armature with a plunger, wherein the plunger is arranged axially moveable within an interior of a sleeve. A pole core insert is at least partially received in the interior. The sleeve includes a coil carrier for receiving the coil that is to be loaded with a voltage. The pole core insert closes the interior of the sleeve relative to the switching valve that is arrangeable opposite to the pole core insert. At an end of the sleeve that is configured oriented towards the pole core insert a lip of the sleeve configured as a lip disc is arranged which is positioned between the coil carrier and a conical disc supporting the pole core insert, wherein the lip closes a cavity of the actuator relative to the hydraulic fluid of the actuator wherein the cavity is largely formed by the coil carrier.
An actuator for a hydraulic valve which includes a cylindrical sleeve can be derived from the patent document DE 10 2009 043 320 B4. The actuator is configured for a hydraulic valve of a cam phaser with a magnet housing which is used for receiving a magnetized metal sleeve or a magnet. The metal sleeve envelops a coil radially which is configured for generating a magnetic field. The coil is received non moveable in a non-magnetizable coil carrier that is positioned in the magnet housing. A non-magnetize able sleeve forms a divider wall between an interior cavity of the sleeve and a pole core and a pole core yoke that is axially offset from the pole core, which are at least partially enveloped by the pole carrier and arranged in a cavity of the magnet housing. In the sleeve an axially moveable armature and a plunger operatively connected with the armature are arranged for positioning a valve piston of the hydraulic valve. The sleeve closes the interior relative to the cavity using a disc shaped lip configured at the sleeve at an end oriented towards the hydraulic valve. A pole core insert mostly received in the interior closes the interior relative to the hydraulic valve, wherein a seal element is arranged between the lip and the hydraulic valve.